My 2011 27 inch iMac will not boot, it plays the startup sound and then freezes on a white screen. I am fairly confident I could fix it myself if I could get it to boot from a USB drive or external disk but holding Option ⌥ during boot does not bring up the boot selector.
Is there another way to get it to boot from a different drive without using Option ⌥?
For example, if I attach an external drive with OS X installed will it automatically boot from it?
edit: I found this page which sounds exactly like what the problem is. So I am looking for another way to replicate what they are accomplishing, by disconnecting the cable, without having to remove the glass.